Stereo moiré technique: A novel 3-d measurement method using a stereo camera and a digital pattern projector

This article deals with a novel 3-D sensor system that employs a measurement technique called the Stereo Moiré technique. The general Moiré method, which is well known for fast and accurate 3-D measurement, has suffered from an inherent limitation in that it cannot measure the absolute 3-D depth due to 2π ambiguity caused by regularity of fringe. In this article, to overcome this 2π ambiguity and obtain the exact depth value effectively, a novel method is proposed. The measurement system consists of a digital pattern projector and two cameras, which can indirectly detect two phase information on the fringe patterns projected onto an object's surface. These two phase values are different due to the difference in camera position. However, the depth values obtained at two different phase information must be identical because the two cameras look at the same point on the object being measured. To verify the efficiency and accuracy of the proposed method, a series of experimental tests was performed. Through the experiments, it is shown that the proposed method can effectively overcome the 2π ambiguity of the typical Moiré technique, and obtain the absolute depth value of the 3-D scene geometric information with satisfactory accuracy.